1 /* 2 * Copyright 2014 Google Inc. 3 * 4 * Use of this source code is governed by a BSD-style license that can be 5 * found in the LICENSE file. 6 */ 7 8 #include "gm.h" 9 #include "sk_tool_utils.h" 10 #include "SkCanvas.h" 11 #include "SkPaint.h" 12 #include "SkRandom.h" 13 #include "SkSurface.h" 14 15 namespace skiagm { 16 17 /* 18 * This GM exercises SkCanvas::discard() by creating an offscreen SkSurface and repeatedly 19 * discarding it, drawing to it, and then drawing it to the main canvas. 20 */ 21 class DiscardGM : public GM { 22 23 public: DiscardGM()24 DiscardGM() { 25 } 26 27 protected: onShortName()28 SkString onShortName() override { 29 return SkString("discard"); 30 } 31 onISize()32 SkISize onISize() override { 33 return SkISize::Make(100, 100); 34 } 35 onDraw(SkCanvas * canvas)36 void onDraw(SkCanvas* canvas) override { 37 GrContext* context = canvas->getGrContext(); 38 if (nullptr == context) { 39 return; 40 } 41 42 SkISize size = this->getISize(); 43 size.fWidth /= 10; 44 size.fHeight /= 10; 45 SkImageInfo info = SkImageInfo::MakeN32Premul(size); 46 auto surface = SkSurface::MakeRenderTarget(context, SkBudgeted::kNo, info); 47 if (nullptr == surface) { 48 return; 49 } 50 51 canvas->clear(SK_ColorBLACK); 52 53 SkRandom rand; 54 for (int x = 0; x < 10; ++x) { 55 for (int y = 0; y < 10; ++y) { 56 surface->getCanvas()->discard(); 57 // Make something that isn't too close to the background color, black. 58 SkColor color = sk_tool_utils::color_to_565(rand.nextU() | 0xFF404040); 59 switch (rand.nextULessThan(3)) { 60 case 0: 61 surface->getCanvas()->drawColor(color); 62 break; 63 case 1: 64 surface->getCanvas()->clear(color); 65 break; 66 case 2: 67 SkPaint paint; 68 paint.setShader(SkShader::MakeColorShader(color)); 69 surface->getCanvas()->drawPaint(paint); 70 break; 71 } 72 surface->draw(canvas, 10.f*x, 10.f*y, nullptr); 73 } 74 } 75 76 surface->getCanvas()->discard(); 77 } 78 79 private: 80 typedef GM INHERITED; 81 }; 82 83 ////////////////////////////////////////////////////////////////////////////// 84 85 DEF_GM(return new DiscardGM;) 86 87 } // end namespace 88